Many parts of the United States have insufficient rain fall during portions of the year to support healthy landscape vegetation. Rotor-type sprinklers, rotary stream sprinklers and spray-type sprinklers are therefore frequently employed to water turf and plants associated with residences, apartments, and playing fields. Water shortages have led many states and municipalities, and more recently the EPA, to promulgate and/or impose landscape watering restrictions to conserve water. Efforts have therefore been made by companies in the irrigation industry to design more water efficient sprinklers and water conserving electronic irrigation controllers. The latter frequently use rain sensors, and in some cases, watering schedules that are altered based on evapotranspiration (ET) data. One way to conserve water when irrigating plants and shrubs is to employ so-called micro-irrigation systems, such as drip irrigation. Water is delivered at very low flow volumes to drip emitters and micro-spray nozzles placed closely adjacent to plants, shrubs and trees. This eliminates most of the water waste primarily associated with spray-type sprinklers that deliver water at high flow volume rates and produce significant water run-off and wind-blown mist.
When drip irrigation is utilized, plants often receive more water than is necessary to maintain their health. This is because homeowners and landscape maintenance personnel have very limited visual feedback about the amount of water that is being delivered. Water that seeps into the surrounding soil often penetrates deeply below the roots of the plants. Sometimes the soil around the plants already has sufficient moisture to maintain plant health or only a minimal amount of water is needed that is less than that provided by the watering program executed by the irrigation controller. Excess water is often absorbed by the soil, and there is no visible puddling or run-off. By way of example, a landscape area with several hundred drip emitters running at two gallons per hour can easily waste hundreds of gallons of water in one cycle of a watering program executed by an irrigation controller.